Discharge tube provided with an electrode comprising nickel and aluminum

ABSTRACT

The invention relates to a gas and/or vapour discharge tube provided with an electrode consisting of several metal layers running parallel to one another. According to the invention the electrode consists of niferal material (nickel, iron, aluminum) which has been subjected to a given thermal treatment so that the discharge only terminates on the nickel layer.

United States Patent [111 3,908,252

Willems 1 Sept. 30, 1975 DISCHARGE TUBE PROVIDED WITH AN ELECTRODE COMPRISING NICKEL AND ALUMINUM Inventor: Henricus Gerardus Antonius Willems, Terncuzen, Netherlands Assigncc: U.S. Philips Corporation, New

York, NY.

Filed: Aug. 20, 1973 Appl. No: 389,676

Foreign Application Priority Data Sept. 12. 1972 Netherlands 7212336 U.S. Cl. 29/25.17; 29/25.l5; 117/227;

148/131; 313/346 R; 313/353 Int. CL HOlJ 9/00 Field of Search v. 313/210 217, 346 R, 353; 29/25.]5. 25.17, 196.2; 117/217, 227; l48/l3.1

[56] References Cited UNITED STATES PATENTS 2459.51 1 H1949 Elmcndorf 313/210 3.530.559 9/1970 Kerstetter... 29/2517 3.753.024 8/1973 Vicai..... 313/217 Primary E.\'aminerEli Lieberman Attorney, Agent, or FirnzFrank R. Trifari 5 7 ABSTRACT The invention relates to a gas and/or vapour discharge tube provided with an electrode consisting of several metal layers running parallel to one another.

According to the invention the electrode consists of niferal material (nickel, iron, aluminum) which has been subjected to a given thermal treatment so that the discharge only terminates on the nickel layer.

6 Claims, 4 Drawing Figures EMITTER U.S. Patent Sept. 30,1975 Sheet 1 of2 3,908,252

Fig.2

U.S. Patent Sept. 30,1975 Sheet 2 of2 3,908,252

EM ITT E R s DISCHARGE TUBE PROVIDED WITH AN ELECTRODE COMPRISING NICKEL AND ALUMINUM The invention relates to a method of manufacturing a gas and/or vapour discharge tube in which the discharge tube is provided with an internal electrode and in which this electrode consists of at least a layer of aluminium and a layer of nickel running parallel thereto, a step being taken of facilitating the emergence of electrons from the side of the nickel layer remote from the aluminium. The invention also relates to a gas and/or vapour discharge tube manufactured by this method.

A known method of the kind mentioned above is described, for example, in US. Pat. Spec. No. 2,459,511. A drawback of this known method is that the side of the aluminium layer remote from the nickel is to be provided with an extra coating so as to cause the discharge, in the operating condition of the lamp, to terminate on the nickel side.

An object of the invention is to provide a simple process for the method of the kind described so as to cause the discharge to terminate on the nickel side of the electrode.

According to the invention a method of manufacturing a gas and/or vapour discharge tube in which the discharge tube is provided with an internal electrode and in which said electrode consists of at least a layer of aluminium and a layer of nickel running parallel thereto and in which a step is taken of facilitating the emergence of electrons from the side of the nickel layer remote from the aluminium is characterized in that niferal having an aluminium layer less than microns thick is used as a starting material (raw material) for the electrode, said niferal being maintained in a non oxidizing atmosphere for a maximum period of 15 minutes at a temperature of at least 700C.

In this connection niferal is to be understood to mean a commercially available laminar sandwich assembly which consists of three parallel layers the inner one of which is iron and the other layers consist of nickel and aluminium. Each layer is uniform throughout in composition and cross-section. The ferrous alloy or steel core consists of approximately 98 per cent iron and contains a small addition of manganese and carbon in addition to some impurities. The nickel layer is approximately 99 per cent pure and has as its main impurities iron and manganese. The aluminum layer is also approximately 99 per cent pure and has as its main impurity silicon. It will be understood that this description of the niferal sandwich relates to the material which is provided initially in accordance with the method of the invention.

An advantage ofa method according to the invention is that the relatively high work potential of the aluminium side of niferal is brought about by diffusion of iron into aluminium. As a rule this produces a black colour on the outer side of the aluminium layer. This aluminium layer then need not be provided with a further coating.

In a preferred method according to the invention the thermal treatment of niferal of the electrode is not effected until after the electrode is positioned in the discharge tube.

An advantage thereof is that the risk of possible damage of the electrode during further manufacture is only small.

In a further preferred embodiment according to the invention in which the step of facilitating the emergence of the electrons from the nickel layer consists of providing said nickel layer with an emitter which is provided on the nickel in the form of one or more carbonates converted into oxides during a thermal treatment, the thermal treatment of the emitter and the thermal treatment of niferal is effected during one and the same heating process during which the temperature is maintained between 1000C and I100C for 5 to 15 seconds.

An advantage of this preferred method is that one manufacturing stage is accomplished dual tasks.

A discharge lamp manufactured in accordance with a method according to the invention is preferably a glow-discharge lamp having a sheet-like electrode with the nickel side of the electrode being provided with an emitter, whereby the nickel side faces the light emergence side of the lamp.

An advantage of this embodiment is that a glowdischarge lamp can be obtained having a relatively low ignition voltage and that a satisfactory part of the electrodes is covered with glow discharge light.

In a further preferred embodiment of a discharge lamp manufactured by a method according to the invention the lamp is an arc discharge lamp in which the electrode is formed as a hollow electrode with the nickel layer on the inner side.

This embodiment gives a preference to the nickel side as regards the emergence of electrons so that in this case the nickel layer need not necessarily be provided with an emitter.

An advantage of this preferred embodiment is that a satisfactory electrode can be obtained in a simple manner. The are terminates on the inner side of the hollow electrode so that blackening of the wall of the discharge tube at the area of the electrode is prevented.

The invention will further be described with reference to a drawing.

FIG. 1 shows a glow-discharge lamp according to the invention partly in a cross-section and partly in an elevational view;

FIG. 2 shows an arc discharge lamp according to the invention;

FIG. 3 is a sectional view taken through the line III- III of FIG. 1 and FIG. 4 is a sectional view taken through the line IV 1b-lb of FIG. 2.

In FIG. 1, 1 is a wall of a discharge tube which is filled with neon and argon. The tube 1 accommodates a cupshaped electrode (2) and an annular electrode (3). The cup-shaped electrode (2) is made of niferal whose nickel side is provided with an emitter. This electrode is maintained at I050C in vacuo for 5 to 15 seconds after it is placed in the tube 1. The nickel side of the electrode 2 is remote from the lamp cap 6 and thus faces the light emergence side of the lamp. The emitter on the nickel side consists of a triple carbonate of barium, strontium and calcium decomposed during the said thermal treatment. 4 and 5 are supply wires. The annular electrode 3 is made of nickel.

The ignition and operating voltages of this lamp were lower than volts. The work potential of the aluminium comprising layer (facing the lamp cap) of the electrode 2 was more than 6 volts.

FIG. 2 shows a so-called ozone-lamp which is provided with a quartz tube 20. Both ends of the elongated tube 20 accommodate a hollow main electrode (21 and 22, respectively) of niferal. These main electrodes are heated for approximately minutes at approximately 700C in a dry hydrogen atmosphere before they are introduced into the quartz discharge tube. The nickel is present on the inner side of the (hollow) electrodes 21 and 22. These main electrodes 21 and 22 are not provided with an emitter. The work potential of the aluminium containing (outer) coating was also larger than 6 volt.

Auxiliary electrodes (23 and 24) for the ignition of the lamp are present within the main electrodes (21 and 22, respectively). The tube contains neon and argon and furthermore mercury for generating ultraviolet light for the ozone production.

Both in the lamp of FIG. 1 and that of FIG. 2 the discharge terminates on the nickel side of the main electrodes, in the operating condition of the lamp.

What is claimed is:

l. A method of manufacturing a gas or vapour discharge tube in which the discharge tube is provided with an internal electrode which comprises providing an electrode which comprises a sandwich of layered metals, successive layers being nickel, iron and aluminum. said aluminum layer being less than 15 microns and maintaining said sandwich in a non-oxidizing atmosphere at a temperature of at least 700C for a maximum of 15 minutes.

2. A method as claimed in claim 1, characterized in that the thermal treatment of said sandwich is effected after the step of positioning said electrode in the discharge tube.

3. A method as claimed in claim 2 further includes providing said nickel layer with an emitter which is provided on the nickel in the form of one or more carbonates converted into oxides during said maintaining step, said maintaining including maintaining said sandwich and emitter between 1000C and 1100C for 5 to 15 seconds.

4. A method as described in claim 3 wherein said providing step includes providing an aluminum layer of the electrode which has a work potential of more than 6 volts.

5. A method as claimed in claim 4 for manufacturing a glow discharge lamp, said positioning step including positioning said nickel layer facing the light emergence side of the lamp.

6. A method as claimed in claim 4, for manufacturing an arc discharge lamp, wherein said providing step includes providing an electrode formed as a hollow electrode with its nickel layer on the inner side.

l l l l 

1. METHOD OF MANUFACTRUING A GAS OR VAPOUR DISCHARGE TUBE IN WHICH THE DISCHARGE TUBE IS PROVIDED WITH AN INTERNAL ELECTRIDE WHICH COMPRISES PROVIDED WITH AN INTERNAL PRISES A SANDWICH OF LAYERED METALS, SUCCESSIVE LAYERS BEING NICKEL, IRON AND ALUMINUM, SAID ALUMINUM LAYER BEING LESS THAN 15 MICRONS AND MAINTAINING SAID SANDWICH IN A NON-OXIDIZING ATMOSPHERE AT A TEMPERATURE OF AT LEAST 700*C FOR A MAXIMUM OF 15 MINUTES.
 2. A method as claimed in claim 1, characterized in that the thermal treatment of said sandwich is effected after the step of positioning said electrode in the discharge tube.
 3. A method as claimed in claim 2 further includes providing said nickel layer with an emitter which is provided on the nickel in the form of one or more carbonates converted into oxides during said maintaining step, said maintaining including maintaining said sandwich and emitter between 1000*C and 1100*C for 5 to 15 seconds.
 4. A method as described in claim 3 wherein said providing step includes providing an aluminum layer of the electrode which has a work potential of more than 6 volts.
 5. A method as claimed in claim 4 for manufacturing a glow discharge lamp, said positioning step including positioning said nickel layer facing the light emergence side of the lamp.
 6. A method as claimed in claim 4, for manufacturing an arc discharge lamp, wherein said providing step includes providing an electrode formed as a hollow electrode with its nickel layer on the inner side. 